Spark advance (UVO?!) hose

["content22207" <brobertson@xxxx>]

Unidentified Vacuum Object is the spark advance diaphragm. Moves rotor
button farther from cylinder top at higher RPM's.

If my R30 is representative, 3/16" hose works excellent. You don't
want pretty hose -- you want tough hose. Environment is harsh in
normal engine compartment. In DeLo is positively brutal. HOT. No air
circulation. If you intend to drive the car, get the toughest 3/16"
hose available.

For years I have used fuel line hose in vacuum applications. Holds up
excellent. IMHO looks pretty good too (I'll repost larger pic of upper
air assembly to #5939's photo album. That's my spark advance takeoff,
using fuel line hose, just before throttle plates -- R30 configured a
little differently than stock DeLorean).

Speaking of which: you should not feel any vacuum in line to spark
advance diaphragm at idle. Stock DeLo uses solenoid to shut off until
throttle plates open. If you've got vacuum to diaphragm at idle,
engine is horribly over advanced. Won't really idle unless you over
retard distributor body or over enrich fuel mixture, either of which
will kill performance as throttle plates open.

Note also stock DeLo has vacuum lines to control pressure regulator
and a delay valve, all of which must work properly -- as soon as
throttle plates open full vacuum is shot to spark advance diaphragm.
Is one heck of a jump in ignition time. At previous fuel mixture
you'll get predetonation (spark knock/valve clatter). To compensate
DeLo briefly enriches fuel mixture at CPR . By the time delay valve
equalizes vacuum in the CPR, vacuum spike at spark advance diaphragm
is over. 
Complicated, eh?

IMHO whole arrangement can be simplified greatly (actually, that's
what Renault did with R30):
1) Remove vacuum from CPR. Then becomes warm up regulator only.
2) Move spark advance before throttle plates (like a carburetor). Will
get moderate advance only in time with throttle plate action.

BTW: Extent of my vacuum system is:
-Direct line from upper air assembly to spark advance
-Big line from passenger intake rail to vacuum canister and front of
car (plus little line back to heater core shutoff valve)
-Auxiliary air valve (for fast idle) engineered from BMW between upper
air assembly and cold start tube (I moved from original installation
at driver intake rail for balance)
That's it. Beautifully simple.

Bill Robertson
#5939